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Need to track a pre-rendered 3D object, tacking doesn't work

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Thomas Bunink
Need to track a pre-rendered 3D object, tacking doesn't work
on Jun 16, 2016 at 11:36:45 am

So this is a tough one:

I need to add a few graphics on the screen of a 3D cell phone, that has been pre-rendered by an old co-worker who no longer works here, and no longer has the original Cinema 4D files. So I can't just paste it in that way.

He did add a green screen on the phone so anything could be pasted in, but the screen is half blocked by something during the animation, so a shadow falls over the phone. Meaning that the green screen is about 155 different shades of green during the animation, and that's no good to me.

I tried motion tracking by way of the 3D camera tracker (didn't work because the video itself is in RGB + Alpha), Normal Motion track (Doesn't work because there is like no contrast on the model) and Mocha. Mocha does a pretty good job of capturing how the movement goes, but the Null seems to be getting the wrong information. I'm a frequent Mocha user, so I'm sure I'm extracting the right tracking data.

So anyone any idea's how to do this? It's getting to the point where I nearly just go "F*** it! I'm out"


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Joe Clay
Re: Need to track a pre-rendered 3D object, tacking doesn't work
on Jun 17, 2016 at 6:00:22 am

I would've said Mocha. If the null is coming in incorrectly, check things like frame rate. If you're tracking a 3D sequence it's likely your frame rate is exactly 24 or 30 or whatever but maybe your AE comp is 23.976 or 29.97.

You could try another 3D tracker like Boujou or something. But if Mocha is unable to track a plane, that seems like it might just not work. You can try to hand keyframe the corners with a corner pin and then track out whatever crosses the screen, but that's probably not going to look the greatest. :/

Joe Clay
Workbench.tv


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Thomas Bunink
Re: Need to track a pre-rendered 3D object, tacking doesn't work
on Jun 17, 2016 at 6:11:49 am

Wound up doing the latter. Worked, but as you said: didn't look too great


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Joe Clay
Re: Need to track a pre-rendered 3D object, tacking doesn't work
on Jun 17, 2016 at 7:26:23 pm

If you're still working on it, it might be worth a shot to try the Smoother. It can smooth out your hand track and it might help. Or it can make it worse, haha. That's kind of how those things go in AE unfortunately. But it's always worth a shot.

Joe Clay
Workbench.tv


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Michael Szalapski
Re: Need to track a pre-rendered 3D object, tacking doesn't work
on Jun 17, 2016 at 9:56:40 pm

I would hunt really hard for that C4D file.

Whoever put green in there is a bit of a goofball anyway. It's much, much, much better to do an object buffer pass. That way you can get the proper reflections, etc. without having to try silly keying tricks. Heck, if they were smart, they would have given you shadow and reflection passes too...

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Joe Clay
Re: Need to track a pre-rendered 3D object, tacking doesn't work
on Jun 17, 2016 at 9:59:25 pm

Yeah, green for device displays in a 3D render makes zero sense. We don't even shoot displays like that anymore.

Joe Clay
Workbench.tv


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hanna dean
Re: Need to track a pre-rendered 3D object, tacking doesn't work
on Jun 18, 2016 at 12:48:38 am

what i do is with mocha is i do alot of checks with the video why it cannot track it what is causing the track issues ,

color
brightness
sharpness
pixels.
video format

if you have checked all them and not worked , create image sequence mocha tracks it super smooth and fast and accurate then movie file.


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